How many large-scale bridging standards do we need?

Someone had a “borderless data center mobility” dream a few years ago and managed to infect a few other people, resulting in a networking industry pandemic that is usually exhibited by the following “facts”:

  • Unhindered Virtual Machine mobility across the globe is the absolute prerequisite for any business agility. Wrong. There are other field-proven solutions and although inter-site VM mobility has been demonstrated, it’s still a half-baked idea and has many caveats.
  • You can only reach that Holy Grail by extending your layer-2 domains across vast distances. Totally wrong. It would be easier to fix L3 routing and signaling protocols than to invent completely new technologies trying to fix L2 problems. Users of Microsoft NLB are might disagree ... in which case I wish them luck in scaling their architecture.
  • Large-scale bridging is absolutely mandatory if you want to build cloud solutions with tens of thousands of servers. Not sure about that. Google is there, Facebook, Twitter and Amazon are (at least) close, large web hosting providers have been around for years ... and yet they somehow managed to survive with existing technologies and good network designs.

Just today XKCD published a very relevant comic, so I can skip my usually sarcastic comments and focus on the plethora of emerging large-scale bridging standards and implementations. Let’s walk through them:

Traditional Service Provider solutions: pseudowires (with EoMPLS or L2TPv3) and VPLS.

Do-it-yourself solutions relying on IP core: L2TPv3 or OTV.

Shortest-path bridging: TRILL and 802.1aq. Within 802.1aq, you have two incompatible implementations of the forwarding plane: SPBV and SPBM. And then there’s Cisco’s FabricPath, which looks to be enhanced 802.1aq at the moment.

While these technologies supposedly target large-scale LAN networks, they’ll soon escape into the WAN (why couldn’t you run 802.1aq SPBM or TRILL over VLPS, for example).

There’s more to come. As if the existing solutions wouldn’t be enough, Juniper & Alcatel-Lucent created their own BGP MPLS Based MAC VPN, which looks to be their response to OTV. As Andrew S. Tanenbaum said “The nice thing about standards is that you have so many to choose from.”

While it’s wonderful to see the explosive bursts of innovation, it might be high time for the IT vendors to stop their market-share-focused jostling and me-too technology launches and focus on what their customers need: stable field-proven interoperable standardized solutions. Everything else will just increase the FUD level ... or maybe that’s not a bad idea considering that I work for a consulting/system integration company.


  1. Faced once the need of larger bridging, but not across the geographic locations. Specific need for virtualisation platform, needed to migrate VPS-s between hardware nodes without changin IP addreses. Pitty..
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